Table 1.
Characteristics of included trials
| Study | Patients (MgSO4/control) | Surgery | Anesth-esia strateg-y | Intervention | Control | Postoperative analgesia |
|---|---|---|---|---|---|---|
| Aly 2011 | 30/30 | Orthoped-ic surgeries | EA | bupivacaine 0.5% + 50 mg magnesium sulphate (MgSO4) in 10 ml as an initial bolus dose followed by infusion of 10 mg/ h (2 ml/h) during the surgery. | N/S in same volume | When surgery was completed, all patients received PCEA using a PCEA device containing fentanyl 2 μg/ml and bupivacaine 0.03% (0.3 mg/ml). The PCEA was programmed to deliver 2.5 ml/h infusion with a bolus dose of 1.5 ml on demand. The lockout interval between boluses was 6 min. If patients had inadequate analgesia, supplementary rescue analgesia with intramuscular pethidine 50 mg was available. |
| Daabiss 2013 | 40/40 | Total knee replacem-ent surgery | EA | Bupivacaine 0.5% + 50 mg magnesium sulphate (MgSO4) in 10 ml as an initial bolus dose followed by infusion of 10 mg/h (diluted in 10 ml saline) during the surgery. | N/S in same volume | When surgery was complete, all patients received PCEA using a PCEA device containing fentanyl 2 μg/ml and bupivacaine 0.08%. The PCEA was programmed to administer a demand bolus dose of fentanyl 5 ml with no background infusion and lockout interval 20 min. If patients had inadequate analgesia, supplementary rescue analgesia with intramuscular pethidine 50 mg was available. |
| Elshark-awy 2018 | 30/30 | Cesarean section | EA | Epidural 20 ml levobupivacaine hydrochloride 0.5% followed by 5 ml of 10% preservative-free MgSO4(500 mg) prepared in two separate syringes | N/S in same volume | If the recorded VAS was ≥3, the patient was given diclofenac potassium 75 mg oral tablets as the first rescue analgesia every 12 h. If the VAS was still > 3 within 30 min, patients were given incremental dose of 0.5 μg/kg fentanyl. |
| Ghatak 2010 | 30/30 | Lower abdomina-l and lower limb surgeries | EA | Bupivacaine 0.5% (19 ml) + magnesium sulphate 50 mg (in 1 ml 0.9% saline) | N/S in same volume | In the event of pain, (VAS ≥40), both intraoperatively as well as postoperatively, a bolus of epidural bupivacaine 0.25% (8 ml) was administered by the anaesthesiologist inside the operation theatre and the nursing staff in the recovery room |
| Gupta 2013 | 30/30 | Total abdomina-l hysterectomies | EA | 1 ml of 50 mg/ml magnesium sulphate in 10 ml epidural anaesthetic solution (9 ml 0.125% bupivacaine) | N/S in same volume | If patients had inadequate analgesia (VAS > 3), epidural fentanyl 1mcg/kg in 10 ml normal saline was administered as supplementary rescue analgesic. |
| Moham-mad 2015 | 20/20 | Unilatera-l thoracic surgery | GA + EA | Toward the end of the surgery, approximately 20 min prior to anticipated extubation. Bupivacaine 0.25% 8 ml + magnesium sulfate 50 mg in 1 ml 0.9% saline. | N/S in same volume | Epidural infusion with 5 ml/h of 0.1% bupivacaine was started 15 min after the bolus dose, and it was continued during the postoperative period via epidural catheter using an infusion pump. Patients complaining of pain in the postoperative period with VAS score ≥ 4, received tramadol 50 mg IV as rescue analgesia and time to the first request for analgesia was noted. |
| Omar 2018 | 50/50 | Infraumb-ilical abdomina-l and pelvic surgeries | EA | 15 ml mixture of 14 ml levobupivacaine 0.5% + 0.5 ml MgSO410% (50 mg) + 0.5 ml of 0.9 NaCl in epidural catheter at induction then continuous epidural infusion of this mixture by 5 ml/h till the end of the surgery | N/S in same volume | If patients had inadequate analgesia (i.e.,: if VAS ≥4 when measured each hour or if patient expressed intolerable pain in between VAS measurements periods) supplementary rescue analgesic was used, pethidine 1 mg/kg i/m/and paracetamol (Perfalgan®) 1 g i.v. drip. |
| Radwan 2017 | 22/22 | Spine surgeries | GA + EA | 14 ml levobupivacaine 0.5% + 50 mg magnesium sulphate in 1 ml saline. Subsequently continuous epidural infusion of levobupivacaine 0.125% + 2 mg/ml magnesium sulphate. Drugs were prepared in 20 cc syringe and the rate of infusion in each group was 5 ml/h. | N/S in same volume | One gram of iv paracetamol was given to the patients when VAS > 3 and every 8 h thereafter. A second rescue analgesic in the form of 50 mg iv meperidine was given to patients if VAS remained > 3 one hour after iv paracetamol. |
| Shruthi 2016 | 20/20 | Infraumb-ilical surgery | EA | 15 ml of bupivacaine 0.5% + 50 mg of magnesium sulphate (MgSO4) made up to 1 ml. | N/S in same volume | Postoperative analgesia was managed with epidural bolus of bupivacaine 0.125% 8 ml boluses and/or Paracetamol 1 g infusion as per discretion of treating consultants. |
| Shahi 2014 | 40/40 | Lower limb surgery | EA | Bupivacaine 0.5% (14 ml) + magnesium sulfate 50 mg (in 1 ml 0.9% saline) | N/S in same volume | In the event of pain, (VAS ≥40), both intraoperatively as well as postoperatively, a bolus of epidural bupivacaine 0.125% (12 ml) was administered by the anesthesiologist inside the operation theatre and the nursing staff in the recovery room. |
| Sun 2012 | 50/50 | Cesarean section | CSEA | After delivery of the fetus, received 0.1% bupivacaine 10 mL and Mg 500 mg. | Nothing added | Postoperatively, oral diclofenac 12.5 mg was given for rescue analgesia whenever the VAS pain score was > 3 cm |
CSEA Combines spinal epidural anesthesia, EA Epidural anesthesia, GA General anesthesia, N/S Normal saline, VAS Visual analogue scale